JP2022067496A - tire - Google Patents

Abstract

To provide a tire that holds steering stability and anti-uneven wear performance and has grip performance on a wet road upgraded.SOLUTION: A tire 1 has a tread 2. Each of a pair of shoulder land parts 3 has plural wavy sipes 6 and first shoulder lateral grooves 7 whose width is larger than that of the wavy sipes and equal to or smaller than 2 mm. A pair of middle land parts 4 and a crown land part 5 have plural non-wavy sipes 10.SELECTED DRAWING: Figure 1

Description

The present invention relates to a tire.

The following Patent Document 1 describes a tire having a first land portion and a third land portion. The first land portion includes a first lug groove extending from the first edge toward the second edge, a second lug groove extending from the second edge toward the first edge, and the first lug groove. A first vertical narrow groove connecting the second lug groove is provided. The third land portion is provided with a third lateral groove that crosses the land portion and a lateral sipes that extend in a zigzag shape. It is said that such tires can exhibit excellent performance on ice and snow while maintaining steering stability on dry road surfaces.

Japanese Unexamined Patent Publication No. 2018-177095

In recent years, tires for vehicles have been maintained on wet roads and snowy roads (hereinafter, simply "wet") while maintaining steering stability performance (hereinafter, simply referred to as "steering stability performance") and uneven wear resistance performance on dry road surfaces. It is required to improve the grip performance on "roads, etc.").

The present invention has been devised in view of the above circumstances, and the main object of the present invention is to provide a tire having improved grip performance on wet roads and the like while maintaining steering stability performance and uneven wear resistance performance. It is supposed to be.

The present invention is a tire having a tread portion, wherein the tread portion includes a pair of shoulder land portions, a pair of middle land portions adjacent to the inside of each of the pair of shoulder land portions in the tire axial direction, and the said. A first having a crown land portion between a pair of middle land parts, each of the pair of shoulder land parts having a plurality of corrugated sipe and a groove width larger than the corrugated sipe and 2 mm or less. A shoulder lateral groove is provided, and a plurality of non-wave type sipes are provided in the pair of middle land portions and the crown land portion.

In the tire according to the present invention, the shoulder land portion includes a tread end which is an outer end in the tire axial direction, and the outer end in the tire axial direction of the corrugated sipe is a tire shaft rather than the tread end. It is desirable to be located inside the direction.

The tire according to the present invention is provided with a plurality of second shoulder lateral grooves in each of the pair of shoulder land portions, and the inner ends of the second shoulder lateral grooves in the tire axial direction are all wavy. It is desirable that the sipes are arranged outside the tire axial direction from the outer end.

In the tire according to the present invention, the first shoulder lateral grooves are arranged in the tire circumferential direction, and at least one corrugated sipe is provided between the first shoulder lateral grooves adjacent to the tire circumferential direction. Is desirable.

In the tire according to the present invention, it is desirable that the amplitude center line of the corrugated sipe is arranged at a position where the distance in the tire circumferential direction between the first shoulder lateral grooves adjacent to the tire circumferential direction is substantially equally divided.

In the tire according to the present invention, a plurality of the non-wave type sipes are provided in the tire circumferential direction, and the distance in the tire circumferential direction between the non-wave type sipes adjacent in the tire circumferential direction is the distance in the tire circumferential direction. It is desirable that it is smaller than.

In the tire according to the present invention, it is desirable that the corrugated sipe extends from the inner end of each of the pair of shoulder land portions in the tire axial direction toward the outside in the tire axial direction.

In the tire according to the present invention, it is desirable that the outer end of the corrugated sipe in the tire axial direction is located in the range of 40% to 45% of the tread width from the equator of the tire.

In the tire according to the present invention, it is desirable that the non-wave type sipes of each of the pair of middle land portions cross each of the middle land portions.

In the tire according to the present invention, it is desirable that the non-wave type sipe of the crown land portion crosses the crown land portion.

In the tire according to the present invention, it is desirable that the wavy sipe contains two or more unit waves.

It is desirable that the tire according to the present invention has an amplitude of the wavy sipe of 2.0 to 3.0 mm.

The tire according to the present invention has a width Wc in the tire axial direction of the crown land portion and a width in the tire axial direction of each of the pair of shoulder land portions within a range of 89% of the tread width centered on the tire equatorial line. It is desirable that the ratio to Wsh (Wsh / Wc) is 1.3 to 1.6.

In the tire according to the present invention, it is desirable that each of the plurality of corrugated sipe has a length of 103% or less of the width Wsh when the corrugated sipe is a straight line.

In the tire according to the present invention, the land ratio LS of each of the pair of shoulder land portions is smaller than the land ratio LC of the crown land portion within the range of 89% of the tread width centered on the tire equatorial line. Is desirable.

In the tire according to the present invention, it is desirable that the land ratio LS of each of the pair of shoulder land portions is 95% or more of the land ratio LC of the crown land portion.

By adopting the above configuration, the tire of the present invention can improve grip performance on wet roads and the like while maintaining steering stability performance and uneven wear resistance performance.

It is a development view of the tread part of one Embodiment of the tire of this invention. It is an enlarged view of the shoulder land part of FIG. It is an enlarged view of the middle land part and the crown land part of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a developed view of a tread portion 2 of a tire 1 showing an embodiment of the present invention. FIG. 1 shows, for example, pneumatic tires for passenger cars for all seasons. However, the present invention may be applied to pneumatic tires for heavy loads, light trucks, etc., and non-pneumatic tires in which the inside of the tire is not filled with pressurized air.

The tread portion 2 of the present embodiment includes a pair of middle land portions 4, 4 and a pair of middle land portions 4, 4 adjacent to the inside of each of the pair of shoulder land portions 3, 3 and the pair of shoulder land portions 3, 3 in the tire axial direction. It has a crown land 5 between the middle land 4 and 4.

Each shoulder land portion 3 is provided with a plurality of corrugated sipes 6 and a plurality of first shoulder lateral grooves 7 having a groove width larger than that of the corrugated sipes 6 and 2 mm or less. The wave-shaped pavement 6 sucks up the water film on the road surface and enhances the grip performance on wet roads and the like. In particular, since the wave type sipe 6 has a larger amount of water absorption per unit axial length than the non-wave type sipe 10 described later, the grip performance on a wet road or the like is particularly enhanced. The first shoulder lateral groove 7 has an excellent drainage function because the groove width W1 is larger than that of the corrugated sipe. Further, since the groove width W2 of the first shoulder lateral groove 7 is set to 2 mm or less, excessive decrease in the pattern rigidity of the shoulder land portion 3 is suppressed, and uneven wear resistance performance and steering stability performance are maintained.

A plurality of non-wave type sipes 10 are provided in the pair of middle land portions 4, 4 and the crown land portion 5. Compared to the shoulder land portion 3, the middle land portion 4 and the crown land portion 5 tend to have a large contact pressure when traveling straight. As a result, the non-wave type sipe 10 secures the pattern rigidity of the middle land portion 4 and the crown land portion 5, and maintains high steering stability performance and uneven wear resistance performance. A plurality of non-wave type sipes 10 of each middle land portion 4 and crown land portion 5 are provided in the tire circumferential direction.

In the present specification, a sipe refers to a notched body having a width of 1.5 mm or less, and is clearly distinguished from a grooved body having a groove width of more than 1.5 mm. Further, the wave type sipe refers to a wave type sipe having two or more unit waves, and is clearly distinguished from a non-wave type sipe which is a unit wave of one or less. In addition, the non-wave type sipe includes a sipe extending in a straight line without a unit wave. Further, the number of unit waves is the number of one wavelength formed in one sipe. Wavelengths include smoothly extending arcs and sharply extending V-shapes.

The tread portion 2 includes a pair of shoulder main grooves 13 and 13 defining the shoulder land portion 3 and the middle land portion 4, and a pair of crown main grooves 14 and 14 defining the middle land portion 4 and the crown land portion 5. Includes. In this embodiment, each shoulder main groove 13 and each crown main groove 14 extend continuously in the tire circumferential direction. Each shoulder main groove 13 and each crown main groove 14 are provided on both sides of the tire equator C, for example. The tread portion 2 of the present embodiment is formed as a point symmetry pattern at an arbitrary point on the tire equator C. The tread portion 2 is not limited to the point symmetry pattern.

The shoulder main groove 13 and the crown main groove 14 each include an outer groove edge 15 arranged on the outer side in the tire axial direction and an inner groove edge 16 arranged on the inner side in the tire axial direction from the outer groove edge 15. I'm out. The outer groove edge 15 extends linearly along the tire circumferential direction, for example. The inner groove edge 16 extends in a crank shape in the tire circumferential direction, for example. Each inner groove edge 16 has a first portion 16a extending linearly in the tire circumferential direction, a second portion 16b extending linearly on the tire equatorial line C side of the first portion 16a, and a first portion. It includes a third portion 16c that connects the 16a and the second portion 16b and extends linearly. The first portion 16a and the second portion 16b extend, for example, along the tire circumferential direction. The third portion 16c is connected to, for example, a lateral groove or a sipe, which will be described later.

In the present embodiment, the groove width Wa of the shoulder main groove 13 is formed to be larger than the groove width Wb of the crown main groove 14. The groove width Wa of the shoulder main groove 13 is, for example, 3.5% to 5.5% of the tread width TW. The groove width Wb of the crown main groove 14 is, for example, 3.0% to 5.0% of the tread width TW.

The shoulder land portion 3 includes a tread end Te which is an outer end in the tire axial direction. The tread end Te is a ground contact position on the outermost side in the tire axial direction of the ground contact surface where a normal load is applied to the tire 1 in a normal state and the tire 1 is grounded on a flat surface at a camber angle of 0 °. In the present specification, unless otherwise specified, the dimensions and the like of each part of the tire 1 are values measured in this normal state. The distance between the tread ends Te and Te on both sides in the tire axial direction is the tread width TW.

The "normal state" is a no-load state in which the tire 1 is rim-assembled on a normal rim (not shown) and is filled with a normal internal pressure.

The "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire 1 is based. For example, "standard rim" for JATMA and "Design Rim" for TRA. If it is ETRTO, it is "Measuring Rim".

The "regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire 1 is based. If it is JATMA, it is the "maximum air pressure", and if it is TRA, it is the table "TIRELOAD LIMITSAT". The maximum value described in "VARIOUSCOLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

The "regular load" is the load defined for each tire in the standard system including the standard on which the tire is based. For JATMA, "maximum load capacity", for TRA, the table "TIRE" The maximum value described in "LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", or "LOAD CAPACITY" for ETRTO.

FIG. 2 is an enlarged view of the shoulder land portion 3 of FIG. As shown in FIG. 2, the shoulder land portion 3 of the present embodiment is further provided with a second shoulder lateral groove 8, a circumferential sipe 9, and a non-wave type sipe 10. The second shoulder lateral groove 8, the circumferential sipe 9, and the non-wave type sipe 10 are arranged, for example, on each shoulder land portion 3 in the tire circumferential direction.

The outer end 6e of the corrugated sipe 6 in the tire axial direction is located inside the tread end Te in the tire axial direction. As a result, an excessive decrease in the rigidity of the shoulder land portion 3 is suppressed.

The corrugated sipe 6 extends from the inner end 3i of the shoulder land portion 3 in the tire axial direction toward the outside in the tire axial direction. Such a corrugated sipe 6 can discharge the water film sucked into the wavy sipe 6 to the shoulder main groove 13. Further, since the corrugated sipe 6 can be greatly deformed at the time of touchdown, a large amount of water film can be sucked into the inside.

The wave type sipe 6 preferably includes, for example, two or more unit waves, and more preferably three or more unit waves. As a result, the above-mentioned action is effectively exerted. In order to maintain high steering stability performance, the wave type sipe 6 preferably contains 8 or less unit waves, and more preferably 6 or less unit waves.

The amplitude λ of the wavy sipe 6 is 2.0 to 3.0 mm in this embodiment. Such a wave-shaped sipe 6 can enhance the water absorption effect while suppressing an excessive decrease in the rigidity of the shoulder land portion 3. In the present specification, the amplitude λ is the distance between the two points most separated from each other on both sides in the orthogonal direction with the amplitude center line 6s of the wavy sipe 6.

Within the range of 89% of the tread width centered on the tire equatorial line C, the corrugated sipe 6 has a length LT (not shown) when the corrugated sipe 6 is made into one straight line, and the shoulder land portion 3 has a length LT (not shown). It is desirable that it is 103% or less of the width Wsh in the tire axial direction. As a result, uneven wear resistance and steering stability are maintained high. The length when the wavy sipe 6 is a straight line is preferably 85% or more, more preferably 90% or more, and further preferably 98% or less of the width Wsh of the shoulder land portion 3.

The outer end 6e of the corrugated sipe 6 in the tire axial direction is located in the range of 40% to 45% of the tread width TW from the tire equator C. Since the outer end 6e of the corrugated sipe 6 is located in a range of 40% or more of the tread width TW from the tire equator C, the grip performance on a wet road can be effectively improved. Since the outer end 6e of the corrugated sipe 6 is located within a range of 45% or less of the tread width TW from the tire equator C, it is possible to maintain high uneven wear resistance performance and steering stability performance. The length L1 in the tire axial direction of the corrugated sipe 6 is, for example, preferably 55% or more, more preferably 60% or more, preferably 75% or less, and 70% or less of the width Ws in the tire axial direction of the shoulder land portion 3. Is even more desirable.

Although not particularly limited, the depth of the corrugated sipe 6 (not shown) is, for example, preferably 3 mm or more, more preferably 4 mm or more, preferably 7 mm or less, and even more preferably 6 mm or less.

At least one corrugated sipe 6 is provided between the first shoulder lateral grooves 7 and 7 adjacent to each other in the tire circumferential direction. For example, one corrugated sipe 6 may be provided between the first shoulder lateral grooves 7, and two corrugated sipes 6 may be provided. This is determined by the distance Ls in the tire circumferential direction between the first shoulder lateral grooves 7. That is, when the distance Ls is large, two corrugated sipes 6 are provided, and when the distance Ls is small, one corrugated sipes 6 is provided. As a result, uneven wear resistance and steering stability are maintained high.

The amplitude center line 6s of the corrugated sipe 6 is arranged at a position where the distance Ls between the first shoulder lateral grooves 7 adjacent to each other in the tire circumferential direction is substantially equally divided. As a result, in particular, the uneven wear resistance is maintained high. The substantially equal division includes not only the equal division of the distance Ls but also the range shifted in the tire circumferential direction within 15% of the distance Ls from the equally divided position.

The first shoulder lateral groove 7 is formed, for example, on a convex arc on one side (upper side in FIG. 2) in the tire circumferential direction. In the present embodiment, the first shoulder lateral groove 7 extends from the inner end 7i arranged in the shoulder land portion 3 to the outside in the tire axial direction beyond the tread end Te. Since the water in the first shoulder lateral groove 7 is discharged to the outside of the tread end Te, the grip performance is enhanced.

The distance La in the tire axial direction between the inner end 7i of the first shoulder lateral groove 7 and the inner end 3i of the shoulder land portion 3 is preferably 10% or more, and more preferably 15% or more of the width Ws of the shoulder land portion 3. , 30% or less is desirable, and 25% or less is even more desirable. Since the distance La is 10% or more of the width Ws, an excessive decrease in the rigidity of the shoulder land portion 3 is suppressed. Since the distance La is 30% or less of the width Ws, the water film between the road surface and the tread surface can be effectively discharged.

The second shoulder lateral groove 8 extends beyond the tread end Te from the inner end 8i in the tire axial direction arranged in the shoulder land portion 3 toward the outside in the tire axial direction. Such a second shoulder lateral groove 8 also enhances grip performance.

The inner end 8i of the second shoulder lateral groove 8 is arranged outside the outer end 6e of the corrugated sipe 6 in the tire axial direction. As a result, the second shoulder lateral groove 8 and the corrugated sipe 6 do not overlap in the tire axial direction, so that the decrease in the tire circumferential rigidity of the shoulder land portion 3 is further suppressed. The distance Lb in the tire axial direction between the inner end 8i of the second shoulder lateral groove 8 and the outer end 6e of the corrugated sipe 6 is preferably 5% or less of the width Ws of the shoulder land portion 3, and more preferably 3% or less. .. The distance Lb may be 1% or more of the width Ws of the shoulder land portion 3.

The groove width W2 of the second shoulder lateral groove 8 is preferably 90% or more, more preferably 95% or more, preferably 110% or less, and further preferably 105% or less of the groove width W1 of the first shoulder lateral groove 7. As a result, the above-mentioned effects are effectively exhibited.

The circumferential sipe 9 extends linearly along the tire circumferential direction, for example. Such a circumferential sipe 9 maintains high uneven wear resistance. The circumferential sipe 9 may extend in a wavy shape.

The circumferential sipe 9 connects the first shoulder lateral grooves 7 and 7 adjacent to each other in the circumferential direction of the tire. Such a circumferential sipe 9 is greatly deformed when it touches the ground, and can suck up a large amount of water on the road surface.

The circumferential sipe 9 intersects the wavy sipe 6. As a result, the above-mentioned action is effectively exerted. The circumferential sipe 9 intersects the central portion 6c of the corrugated sipe 6 in the tire axial direction. Such a circumferential sipe 9 also promotes deformation of the corrugated sipe 6 to further enhance grip performance on wet roads and the like. In the present specification, the central portion 6c of the corrugated sipe 6 refers to a range within 10% of the length L1 of the corrugated sipe 6 from the intermediate position in the tire axial direction of the corrugated sipe 6 to both sides in the tire axial direction.

The non-wave type sipe 10 of the shoulder land portion 3 extends linearly. The non-wave type sipe 10 extends outward from the inner end 3i of the shoulder land portion 3 in the tire axial direction and is connected to the inner end 7i of the first shoulder lateral groove 7. Such a non-wave type sipe 10 increases the deformation of the first shoulder lateral groove 7 at the time of touchdown, and further enhances the grip performance.

FIG. 3 is an enlarged view of the middle land portion 4 and the crown land portion 5 of FIG. As shown in FIG. 3, each middle land portion 4 includes a non-wave type sipe 10 and a middle lateral groove 17 extending in the tire axial direction. The non-wave type sipe 10 includes a middle crossing sipe 18 that traverses the middle land 4 and a middle break sipe 19 at one end that terminates within the middle land 4.

The middle crossing sipe 18 includes, for example, a narrow portion 23 of a small width W3 and a large portion 24 of a width W4 larger than the narrow portion 23. The narrow portion 23 extends outward from the crown main groove 14 in the tire axial direction, for example. In the present embodiment, the narrow portion 23 is inclined to one side with respect to the tire axial direction. The large portion 24 extends from, for example, the narrow portion 23 to the shoulder main groove 13. The large portion 24 is a first large portion 24a that is connected to the narrow portion 23 and is inclined at the same angle as the narrow portion 23, and a second large portion 24b that is inclined at a larger angle with respect to the tire axial direction than the first large portion 24a. And a third large portion 24c that is inclined at an angle smaller than that of the second large portion 24b. The narrow portion 23, the first large portion 24a, the second large portion 24b, and the third large portion 24c each extend linearly, for example. In the present embodiment, the narrow portion 23, the first large portion 24a, the second large portion 24b, and the third large portion 24c are inclined in the same direction with respect to the tire axial direction.

The length L3 of the narrow portion 23 in the tire axial direction is preferably 20% or more, more preferably 25% or more, more preferably 40% or less, still more preferably 35% or less of the width Wm in the tire axial direction of the middle land portion 4. ..

The second large portion 24b is arranged at the central portion 4c in the tire axial direction of the middle land portion 4. The central portion 4c of the middle land portion 4 refers to a range within 10% of the width Wm of the middle land portion 4 from the intermediate position in the tire axial direction of the middle land portion 4 to both sides in the tire axial direction. Such a second large portion 24b reduces the rigidity of the central portion 4c, which has a relatively large rigidity of the middle land portion 4, and equalizes the rigidity of the middle land portion 4 in the tire axial direction. Suppresses the occurrence of wear.

The width W4 of the large portion 24 is less than 1.5 mm. The width W4 of the large portion 24 is preferably 1.2 times or more, more preferably 1.5 times or more, more preferably 2.5 times or less, and further preferably 2.2 times or less the width W3 of the narrow portion 23.

The first large portion 24a of the present embodiment is inclined at the same angle as the third large portion 24c. The first significant portion 24a is not limited to such an embodiment. Further, the angle θ2 of the second large portion 24b is preferably 10 degrees or more larger than the angle θ1 of the first large portion 24a, more preferably 20 degrees or more, and more preferably 50 degrees or less, and 40 degrees. Larger is more desirable below.

The middle interrupted sipe 19 extends, for example, in a straight line. In the present embodiment, the middle interrupted sipe 19 is inclined to one side with respect to the tire axial direction. The middle interrupted sipe 19 of the present embodiment is inclined in the same direction as the narrow portion 23. In the present embodiment, the middle interrupted sipe 19 extends parallel to (the same angle) as the narrow portion 23.

In the present embodiment, the middle interrupted sipe 19 includes a first interrupted sipe 19A extending from the shoulder main groove 13 and a second interrupted sipe 19B extending from the crown main groove 14.

The middle lateral groove 17 extends linearly, for example. The middle lateral groove 17 of the present embodiment is terminated without reaching the central portion 4c of the middle land portion 4. Such a middle lateral groove 17 suppresses a decrease in the rigidity of the middle land portion 4.

The middle lateral groove 17 extends from the shoulder main groove 13 toward the inside in the tire axial direction and terminates in the middle land portion 4, and the middle lateral groove 20 extends from the crown main groove 14 toward the outside in the tire axial direction. It includes an inner middle lateral groove 21 that terminates within the land portion 4. The outer middle lateral groove 20 is connected to the second interrupted sipe 19B. The inner middle lateral groove 21 is connected to the first interrupted sipe 19A. Such an aspect enhances the grip performance of a wet road or the like.

The distance Lm in the tire circumferential direction between the non-wave type sipes 10 and 10 adjacent to each other in the tire circumferential direction of the middle land portion 4 is smaller than the tire circumferential distance Ls (shown in FIG. 2) between the first shoulder lateral grooves 7. Is desirable. As a result, a large number of non-wave type sipes 10 are formed in the middle land portion 4, and the drainage function of the middle land portion 4 which is arranged inside in the tire axial direction and is difficult to drain is enhanced.

It is desirable that the length L4 of the middle lateral groove 17 in the tire axial direction is smaller than the length L3 of the narrow portion 23. The length L4 of the middle lateral groove 17 is preferably 15% or more, more preferably 20% or more, more preferably 35% or less, and further preferably 30% or less of the width Wm of the middle land portion 4.

It is desirable that the groove width W5 of the middle lateral groove 17 is smaller than the groove width W1 of the first shoulder lateral groove 7. As a result, the rigidity of the middle land portion 4 having a relatively high ground pressure is maintained. The groove width W5 of the middle lateral groove 17 is preferably 60% or more, more preferably 65% or more, more preferably 80% or less, and further preferably 75% or less of the groove width W1 of the first shoulder lateral groove 7.

The crown land portion 5 is provided with a non-wave type sipe 10 and a plurality of crown lateral grooves 30.

The non-wave type sipe 10 of the crown land portion 5 crosses the crown land portion 5, for example. The non-wave type sipe 10 of the crown land portion 5 extends linearly. A plurality of non-wave type sipes 10 are provided between the crown lateral grooves 30 adjacent to each other in the tire circumferential direction, and in the present embodiment, two are provided.

It is desirable that the distance Lc in the tire circumferential direction of the non-wave type sipes 10 adjacent to each other in the tire circumferential direction of the crown land portion 5 is smaller than the tire circumferential distance Ls between the first shoulder lateral grooves 7. As a result, a large number of non-wave type sipes 10 are arranged on the crown land portion 5, and the drainage function of the crown land portion 5 which is arranged inside in the tire axial direction and is difficult to drain is enhanced. In the present embodiment, the distance Lc is smaller than the distance Ls even when the crown lateral groove 30 is arranged between the adjacent non-wave type sipes 10 in the tire circumferential direction.

The crown lateral groove 30 extends linearly. One end of the crown lateral groove 30 is connected to the crown main groove 14, and the other end is arranged in the crown land portion 5. The crown lateral groove 30 is terminated without reaching the tire equator C. The length L5 of the crown lateral groove 30 in the tire axial direction is preferably 15% or more, more preferably 20% or more, more preferably 35% or less, and further preferably 30% or less of the width Wc of the crown land portion 5.

The crown lateral groove 30 includes a first crown lateral groove 30A connected to one crown main groove 14A (right side in FIG. 3) and a second crown lateral groove 30B connected to the other crown main groove 14B (left side in FIG. 3). I'm out. The first crown lateral groove 30A intersects with the second virtual line K2 in which the groove width center line 30d of the second crown lateral groove 30B is smoothly extended. The second virtual line K2 traverses the first crown lateral groove 30A in the longitudinal direction. The second crown lateral groove 30B intersects with the first virtual line K1 in which the groove width center line 30c of the first crown lateral groove 30A is smoothly extended. The first virtual line K1 traverses the second crown lateral groove 30B in the longitudinal direction. The second virtual line K2 traverses the first crown lateral groove 30A in the longitudinal direction.

Within the range of 89% of the tread width TW centered on the tire equatorial line C, the ratio of the width Wc in the tire axial direction of the crown land portion 5 to the width Wsh in the tire axial direction of each of the pair of shoulder land portions 3 ( Wsh / Wc) is preferably 1.3 to 1.6. The range of 89% of the tread width TW centered on the tire equator C is a region where a relatively large contact pressure acts in straight running. By defining the ratio of the width of each land portion in this region, the grip performance on wet roads and the like can be effectively improved. Since the ratio (Wsh / Wc) is 1.3 or more, the lateral rigidity of the shoulder land portion 3 is enhanced, and the uneven wear resistance performance and the steering stability performance are maintained. Since the ratio (Wsh / Wc) is 1.6 or less, the lateral rigidity of the crown land portion 5 is maintained high, and the grip performance on a wet road is enhanced. From this point of view, the ratio (Wsh / Wc) is preferably 1.4 or more, and preferably 1.5 or less.

Within the range of 89% of the tread width TW centered on the tire equator C, it is desirable that the land ratio LS of each shoulder land portion 3 is smaller than the land ratio LC of the crown land portion 5. The shoulder land portion 3 tends to have a smaller contact pressure during straight running than the crown land portion 5. As a result, by making the land ratio LS of the shoulder land portion 3 smaller than the land ratio LC of the crown land portion 5, it is possible to maintain high uneven wear resistance. In the present specification, the land ratio is the ratio (S / Sa) of the surface area S of the tread in each land portion to the surface area Sa of the virtual tread obtained by filling all the grooves and sipes in each land portion.

If the land ratio LS of the shoulder land portion 3 is excessively smaller than the land ratio LC of the crown land portion 5, the lateral rigidity of the shoulder land portion 3 becomes small, and the steering stability performance may deteriorate. Therefore, it is desirable that the land ratio LS of the shoulder land portion 3 is 95% or more of the land ratio LC of the crown land portion 5. Although not particularly limited, the land ratio LC of the crown land portion 5 is preferably 89% or more, more preferably 91% or more, and even more preferably 93% or more. The land ratio LM of the middle land 4 is preferably 87% or more, more preferably 89% or more, and even more preferably 91% or more. The land ratio LS of the shoulder land portion 3 is preferably 87% or more, more preferably 89% or more, and even more preferably 91% or more.

Although the particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment and can be modified into various embodiments.

A pneumatic tire of size 255 / 50R20 having the basic pattern of FIG. 1 for a passenger car was prototyped based on the specifications in Table 1. Then, tests were conducted on the grip performance, steering stability performance, and uneven wear resistance performance of each test tire on wet roads and the like. The common specifications and test methods for each test tire are as follows.
Used rim: 20 x 7.5J
Internal pressure: 230kPa (all wheels)

<Grip performance and steering stability performance on wet roads>
Each test tire was mounted on all wheels of a 4000cc SUV passenger car. Then, when the test driver runs the test course on the road surface where the snow starts to melt and a puddle is formed, the asphalt road surface including the puddle with a water depth of 3 mm or less, and the dry asphalt road surface, the stability during traction and braking is performed. The sexuality and operability were evaluated by sensuality. The result is displayed with a score of 100 in Example 1. The larger the value, the better the grip performance and steering stability performance on wet roads.

<Uneven wear resistance>
The test driver sensorially evaluated the state of occurrence of uneven wear of the tread portion 2 after traveling on the dry asphalt road surface. The result is displayed with a score of 100 in Example 1. The larger the value, the better the uneven wear resistance.

As shown in the table, the tires of the examples have improved grip performance on wet roads and the like while maintaining steering stability performance and uneven wear resistance performance.

1 tire 3 shoulder land 4 middle land 5 crown land 6 wavy sipe 7 1st shoulder lateral groove 10 non-wave sipe

Claims (16)

A tire with a tread
The tread portion has a pair of shoulder land portions, a pair of middle land portions adjacent to the inside of each of the pair of shoulder land portions in the tire axial direction, and a crown land portion between the pair of middle land portions. death,
Each of the pair of shoulder land portions is provided with a plurality of corrugated sipes and a plurality of first shoulder lateral grooves having a groove width larger than that of the corrugated sipes and 2 mm or less.
A plurality of non-wave type sipes are provided in the pair of middle land parts and the crown land part.
tire. The shoulder land portion includes a tread end which is an outer end in the tire axial direction.
The tire according to claim 1, wherein the outer ends of the corrugated sipe in the tire axial direction are all located inside the tread end in the tire axial direction. Each of the pair of shoulder land portions is provided with a plurality of second shoulder lateral grooves.
The tire according to claim 2, wherein the inner end of the second shoulder lateral groove in the tire axial direction is arranged outside the outer end of the corrugated sipe in the tire axial direction. The first shoulder lateral grooves are arranged in the tire circumferential direction, and the first shoulder lateral grooves are arranged in the tire circumferential direction.
The tire according to claim 3, wherein the corrugated sipe is provided at least one between the first shoulder lateral grooves adjacent to each other in the tire circumferential direction. The tire according to claim 3 or 4, wherein the amplitude center line of the wavy sipe is arranged at a position where the distance in the tire circumferential direction between the first shoulder lateral grooves adjacent to the tire circumferential direction is substantially equally divided. A plurality of the non-wave type sipes are provided in the tire circumferential direction, and the non-wave type sipes are provided.
The tire according to claim 5, wherein the distance in the tire circumferential direction between the non-wave type sipes adjacent to each other in the tire circumferential direction is smaller than the distance in the tire circumferential direction. The tire according to any one of claims 1 to 6, wherein the corrugated sipe extends from the inner end of each of the pair of shoulder land portions in the tire axial direction toward the outside in the tire axial direction. The tire according to any one of claims 1 to 7, wherein the outer end of the corrugated sipe in the tire axial direction is located in the range of 40% to 45% of the tread width from the tire equator. The tire according to any one of claims 1 to 8, wherein each of the non-wave type sipes of the pair of middle land portions crosses each of the middle land portions. The tire according to any one of claims 1 to 9, wherein the non-wave type sipe of the crown land portion crosses the crown land portion. The tire according to any one of claims 1 to 10, wherein the wavy sipe includes two or more unit waves. The tire according to any one of claims 1 to 11, wherein the amplitude of the wavy sipe is 2.0 to 3.0 mm. Within 89% of the tread width centered on the equator of the tire
The ratio (Wsh / Wc) of the width Wc in the tire axial direction of the crown land portion to the width Wsh in the tire axial direction of each of the pair of shoulder land portions is 1.3 to 1.6. The tire according to any one of 1 to 12. The tire according to claim 13, wherein each of the plurality of corrugated sipe has a length of 103% or less of the width Wsh when the corrugated sipe is a straight line. Within 89% of the tread width centered on the equator of the tire
The tire according to any one of claims 1 to 14, wherein the land ratio LS of each of the pair of shoulder land portions is smaller than the land ratio LC of the crown land portion. The tire according to claim 15, wherein the land ratio LS of each of the pair of shoulder land portions is 95% or more of the land ratio LC of the crown land portion.

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